Diabetes affects more than 300 million people worldwide according to the International Diabetes Federation. Type 1 diabetes and type 2 diabetes involve β cell destruction and/or β cell dysfunction. Diabetic patients, particularly those suffering from type 1 diabetes, could potentially be cured through transplantation of β cells. While cadaveric human islet transplantation can render patients insulin independent for 5 years or longer, such approach is limited due to the scarcity and quality of donor islets (Bellin et al., 2012). Generating an unlimited supply of human β cells from stem cells could provide therapy to millions of patients as only a single cell type, the β cell, likely needs to be produced, and the mode of delivery is well understood: transplantation to a vascularized location within the body with immunoprotection. In addition, screening to identify novel drugs that improve β cell function, survival, or proliferation is also delayed due to limited islet supply and variability resulting from different causes of death, donor genetics, and other aspects in their isolation. As such, a steady, uniform supply of stem-cell-derived β cells would offer a useful drug discovery platform for diabetes. Moreover, genetically diverse stem-cell-derived β cells could be used for disease modeling in vitro or in vivo.